(n.) A genus of fossil horses from the Lower Pliocene. They had three toes on each foot, the lateral ones being small.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). protohippus. Retrieved September 21, 2026, from http://smartdefine.org/protohippus/definitions/2050240 |
| Chicago | Webster's. 2011. "protohippus" http://smartdefine.org/protohippus/definitions/2050240 (accessed September 21, 2026). |
| Harvard | Webster's 2011, protohippus, Smart Define, viewed 21 September, 2026, <http://smartdefine.org/protohippus/definitions/2050240>. |
| MLA | Webster's. "protohippus" 27 May 2011. Web. 21 September 2026. <http://smartdefine.org/protohippus/definitions/2050240> |